Continuing negative sales growth by domestic car makers such as Tata Engineering and Locomotive Co Ltd (BSE:TELC) [Telco] and Ashok Leyland Ltd (BSE:ASOK) in the medium and heavy segment pushed commercial vehicles sales down by 2.89 per cent between April and August. A total of 53,459 commercial vehicles were sold during the first five months of the current fiscal against 55,054 units a year earlier, according to data released by the Society of Indian Automobile Manufacturers (SIAM).